Which company has the most innovative biofuel technology of 2008? Coskata, says Biofuels Digest in listing of top 50 bioenergy companies Monday.

Coskata, in Warrenville, Ill., is developing a process to make ethanol from agricultural wastes or non-food crops. The company, which recently raised $40 million, is building a 40,000-gallon-per-year plant near Pittsburgh to demonstrate its technology, which shreds the feedstock into pieces and heat them at a high temperature to turn them into synthesis gas, which is then converted into fuel.

Other biofuel startups also are developing similar processes, but Coskata is closer to commercial production than most. It plans to develop a commercial refinery in Clewiston, Fla., with U.S. Sugar Corp. (see Coskata Lining Up Sugary Deal).

Biofuel Digest, an online news site in Miami, ranked the biofuel companies based on innovations and how far along the companies are in commercializing their technologies.

Many companies on the list are familiar names to those tracking the emerging biofuel industry. Biofuels promise to be a renewable and cleaner source of transportation fuels, though critics say biofuels – particularly cellulosic ethanol – are hardly better for the environment than mining and burning fossil fuels (see Report: Wind the Best Energy; Nuclear, Coal and Ethanol the Worst).

The U.S. government has been a big biofuel booster, passing a legislation in 2007 that requires the country's refineries to blend 36 billion gallons of bi
ofuels by 2022. Whether the country can meet the mandate remains a big question (see U.S. Won't Meet Its Own Biofuel Mandate).

Algal biofuel startup Sapphire Energy in San Diego took the No. 2 spot on the biofuel ranking, followed by Madison, Wis.-based Virent Energy Systems, which says it's developing all sorts of biofuels using food and non-food feedstocks. Virent is even working with Royal Dutch Shell to convert sugar in plants into a fuel that resembles gasoline rather than ethanol.

Of the 50 companies on the list, 17 are developing cellulosic ethanol while nine are into algal biofuels. Another nine companies are working on other types of biofuel technologies, including converting trash from landfills to fuels.

Solazyme, another algal biofuel startup, made the top 10. The South San Francisco company has figured out a way to grow algae without sunlight by using natural algae that thrives in the dark, as well as engineering its own strains. The company expects to commercialize its algal oil first as an ingredient in cosmetics, such as anti-wrinkle products (see Solazyme Explores Jet-Fuel Market).

Range Fuels, another cellulosic ethanol company, also ranked among the top 10. The Broomfield, Colo.-based company just got a new CEO, David Aldous, who previously worked at Shell. Range Fuels is building its first commercial refinery in Soperton, Ga.

Meanwhile, companies such as Cobalt Biofuels, Bluefire Ethanol, Iogen, Qteros (formerly SunEthanol) and Origin Oil made the top 50 list.

Here are the top 10 companies:

Coskata

Sapphire Energy

Virent Energy Systems

Poet

Range Fuels

Solazyme

Amyris Biotechnologies

Mascoma

DuPont Danisco

UOP

You can check out the rest on the top-50 list at the Biofuels Digest Website.